Method of and apparatus for fluid metering



Feb. 1,525,807

- G. H. GIBSON METHOD OF AND AfPARATUS FOR FLUID METERING Filed Aug. 1,1918 4 Sheets-Sheet 1 f INVENTO ,W m ATTORNEYS I G. H. GIBSON V METHODOF AND APPARATUS FOR FLUID METERING 4 'She etS-Sheet 2 Filed Aug. 1,1918 INVENTOR 1 ATTORNEYS G. H. GIBSON METHOD OF AND APPARATUS FOR FLUIDMETERING Filed Aug. 1, 1.918 4 Sheets-Sheet 5 INWQR 4 (PM sawzg,

v ATTORNEYS Feb. 10, 1925. 1,525,807-

6. H. GIBSON v METHOD OF AND APPARATUS FOR FLUID METERING Filed Aug. 1,1918 4 Sheets-Sheet 4 INVENT R hi4 ATTORNEYS I GEORGE E. GIBSON, FMONTGLAIR, -NEW JERSEY.

METHOD OF AND APPARATUS FOR FLUID METERING.

Application filed August 1, 1918. Serial No. 247,858.

To all whom it may 00720671:

Be it known that I, GEORGE H. GIBSON, a citizen of the United States ofAmerica, and a resident of Montclair, in the county of Essex and Stateof New Jersey, have invented a certain new and useful Improve. ment inMethods of and Apparatus for L Fluid Metering, of which the following isa true and exact description, reference being had to the accompanyingdrawings, which form a part thereof. 7

My present invention comprises improvements especially devised'for usein measuring the rates of flow of fluids such as liquids, gases andvapors, and one of the specific objects of the invention is to provideimproved fluid flow measuring apparatus in which an electric current isautomatically maintained by flow responsive means at a strength which isproportional to, or is a function of the rate of flow of a fluid, andwhich comprises novel electrical provisions for automaticallycompensating for changes in the density of the fluid measured, resultingfrom changes in its temperature or other changes in the condition of thefluid. My

invention is of especialutility in determining the efliciency ofoperation of a steam plant, and my invention, in one of its aspects,consists in the novel means which if have devised for conjointlymeasuring various fluid rates of flow which it is necessary or desirableto know to determine the efficiency of operation of a steam plant. Inparticular my invention comprises improved means for obtaining with asingle electrical meter a measure of a plurality of electrical currentsproportional respectively to therate of feed water supply, steam output,the supply of air to support combustion, etc. p

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification.

For a better understanding of the invention, however, and the advantagespossessed by it reference shoulclbc had to the accompanying drawings anddescriptive matter in which I have illustrated and described preferredembodiments of my invention.

- Of the drawings:

Figure 1 is a diagrammat'crepresentation of a steam plant comprisingassociated means for measuring fluid rates of flow in various conduitsof the system with automatic provisions for correcting, for changes influid density resulting from changes in temperature or pressure, and inthe case of steam for changes in pressure and superheat.

Figure 2 is-an elevation partly in section of one of the electromagneticflow balances employed.

Figure 3 is a diagram of a portion of the apparatus employed in theplant shown in Figure 1.

Figure 4 is an elevation of a portion of a modified electromagneticbalance of moditied construction.

Figure 5 is a section on the line 55 of Figure 4:.

Figure 6 is a diagrammatic representation of the portion of theapparatus shown in Figure l for measuring the liquid fuel sup- I phed tothe furnace.

Figure j? is a diagrammatic representation of the portion of theapparatus shown in Figure l for measuring the flow of saturated steam.

, Figure 8 is a diagrammatic representation of the portion of theapparatus shown in Figure 1 for measuring the flow of superheated steam.

Figure 9 is a diagrammatic representation of a portion of the apparatusshown in-Figure 1 for measuring the preheat given the boiler feed Water.

Figure 10 is a diagrammatic representa- 'tion of the portion of theapparatus of Figure 1 employed to measure the amount of primary airsupplied to the furnace.

Figure 11 is a steam chart illustrating steam laws taken into account inthe conaway and in section of the current regu-- lator employed inFigure 1, and Figure 13 is a section on the line 13-13 of Figure 12.

ln the steam plant diagrannnatically illustrated in Fig. l, A representsthe boiler furnace, and A represents the water tubes, A the steam andwater drum, A the combustion chamber, and A, the stack outlet of thefurnace. The steam generated in the boiler and superheated in thesuperheating coils C of the furnace A, passes in the plant illustratedthrough the conduit C to the steam turbine H. B represents the'boilcrfeed water supply line, and B represents a feed water preheater, shownas mounted in the breeching connecting the outlet from the furnaceproper, to the stack A. The

atmospheric pressure through the conduit- As shown, a bleeder pipe (Jr,leading from an intermediate stage of the turbine H, supplies lowpressure steam for heating or other purposes. Associated with each .ofthe conduits B, C, D, E, F and G are electromagnetic flow balances KB,KC, KD, KE, KF and KG respectively. These balances are all of the samegeneral type and'in fact are shown as identicalin con- I structionexcept that the balance KB comprises a compensating coil not used in theothers, as hereinafter explained. A detailed description of one of thesebalances, for instance balance KF, will thus sutiice for all of thebalances. I

The balance KF is shown in Fig. v2, and the electrical connectionsbetween it and a cooperating resistance element SF of an electricalcurrent regulator, and an electrical measuring instrument M, are shownin Figs. 3 and 6. As shown in Fig. 2, the flow balance KF comprises aframe K rovided with a knife edge pivot K through which the frame ispivotally mounted on a suitable bearing block K The frame K comprises ahorizontal cross arm on which receptacles K and K are mounted atoppositesides of, and at adjustable distances from the vertical planethrough 'the bearing edge of the pivot K The receptacles K and K' arepartially filled with a sealing liquid aswater, mercury or oil, and areconnected at their lower ends by the pipe K. The upper end of thechamber K is connected by a flexible conduit K to a Pitot tube K facingthe flow in the conduit F, and a flexible pipe K transmits the staticpressure from the conduit F to the upper end of the chamber K At thelower end of the frame K there is mounted an electrical coil K", whichplays between stationary coils K connected in series with the coil Kiinthe circuit LF. The movable coil K and the coils K cooperate to form anelectrodynamometer of the Kelvin balance type.

The lower end of the balance frame K carries a contact I which liesbetween, and

,in the neutral position of the apparatus shown in Fig. 2, stands outofengagement with adjustable contacts K and K, which are respectivelyengaged when the balance 1 K oscillates the counter clockwise diotherterminal to the ring S rection or clockwise direction respectively. Theframe K carries a vertically adjustable weight K, and a horizontallyadjustable weight, and these weights should be so adjusted that with theproper amount of sealing liquid in the chambers K and K and connectingtube K and with equal pressures. in the upper ends of the chambers K andK the frame K will be in neutral equilibrium in any position of thelatter within its range of oscillation. The pivoted frame K, with thechambers K and K forms a differential pressure gauge of the tilting U-tube type. Connected to the conduit F, as described, the gauge issubjected to a turning moment by the displacement of sealing liquidtherein resulting from a fluid flow in the conduit F, whichisproportional to the difference between the Pitot tube pressure and thestatic pressure in the conduit. As is hereafter more fully explained,this turning moment is proportional to the square of the velocity offluid flow in the conduit F. The turning'moment impressed upon the gaugeby said pressure differential may be balanced by an electricalcurrent'of suitable strength through the dynamometer windings K and K Since theturning moment impressed on the balance by the current flowing throughthe windings K and K is proportional to the square of that current, thelatter is thus directly proportional to the velocity of fluid flow in.the conduit F, 'An electrical current regulator L is so constructed andconlilo nected to the balance KF, and to the other balances KB, KC, KD,KE and KG that it supplies the dynamometer windings of each of thebalances with an electrical current of the proper strength to normallymaintain the balance in its neutral position.

The regulator L, as shown structurally in Fig. 12, comprises frameworkL, in which is mounted a stationary shaft L On the shaft L there arej'ournalled resistance elements SO, SB, SF, etc, one for each of thebalances KC, KB, KF, KE, KD and KG. Each of these resistance elementscomprises a resistance conductor coiled about an an? nular body ofinsulating material, which, with the resistance conductor coiled aboutit, is clasped between a gear wheel S journalled on the shaft L and aclamping ring S secured to the gear S by screws S On its side oppositeto that, at which the corresponding resistance conductor is located,

each ear S carries a pair of annular contact rings S and S One terminalof the corresponding resistance conductor SO, SB, SF, etc. is connectedto the ring S and the Contact brushes S and 8", carried by the frameworkof the regulator, engage the contact rings S and S respectively, andconnect these rings through the branch conductors 10 and flexiblecontact member S of Fig. 3 to electrical supply conductors 1 and 2respectively. Associated with each of the gears S,

4 tors 1 and 2, or some fraction thereof, de-

pending on the angular adjustment of the gear S on which the resistanceconductor SF is mounted. The dynamometer windings of the balances KB,KC, KD, KE and KG are similarly connected by circuits LB, LO, Ll), LEand LG to the corresponding resistance conductors SB, SC, SD, SE and SGrespectively.

Means are provided for automatically adjusting each of the gears Sseparately about the supporting shaft L". These means, as shown,comprise a constantly running motor L connected by gears L and L to ashaft L journalled in the framework L, and a secondshaft L alsojournalled in the framework L, and carrying a gear L meshing with thegear L Associated with each gear S are a pair of levers L and Ljournalled on the shafts L and L respectively, and each carrying a spurgear L constantly in mesh with a spur gearL secured to the correspondingsupporting shaft L or L Normally the gears L are out of mesh with thegear S, but each of the levers L and L may be oscillated to swing itsgear L into meshwith the corresponding gear S. in mesh with the latterthe gear L carried by the lever L causes the gear S to be driven in onedirection from the motor L through the shaft L and the gear L cafried bythe lever L when in mesh with the gear S, causes the latter to berotated in the opposite direction by the motor L through shaft Lt. Eachof the levers L carries an armature L working above a correspondingelertromagnet T, and each of the levers L carries an armature workingabove a corresponding electromagnet z.-;= The coil windingof theelectromganet '1, associated with the disc S, carrying the resistanceconis connected'by one conductor ductor SF,

contact K of the balance FL between the RF and the branch supplyconductor 10.

the corresponding.

Similarly the winding of electromagnet t is connected by a secondconductor FL between balanCe, KF and the supply conductor. 10,

K of the balance. glzing the winding of the corresponding the'contact Kof the windings of the appropriate electromagnets T and t, and thesource of electrical current by conductors BL, CL, DL, EL

and GL, respectively.

, With the arrangement described, on an increase in the flow through theconduit F and the corresponding increase in the difierence between thepressures transmitted to the upper ends of the chambers K and K there isa resultant movement of the sealing liquid from the chamber K into thechamber K ofthe balance KF, oscillating the latter in the counterclockwise direction, and thereby bringing about'an engagement betweenthe contact K and the contact This results in enerelectromagnet T,whereupon the. lever L is shiftedto bring its gear L int-o mesh with the.gear S carrying the resistance conductor SF. When the latter is thusgeared'to the shaft L the latter turns the gear S in the clockwisedirection and there-- by increases the potential difference between thesupply conductorlO and the brush S engaging the resistance conductor SF,and this turning motion is continued until the voltage thus impressed onthe terminals of the circuit LF, including the coils K and K of thebalanceKF, creates a current flow through those coils strong enough toswing the frame K back'to'the neutral posit-ion and thus separate thecontacts L andK. Similarly, when the displacement of the sealing liquidtakes place from the chamber K into the chamber K" of the bal ance'KF,and the frame K oscillates in the clockwise direction so as to move thecontact K into-engagement with the contact K the correspondingelectromagnet, t is energized, and the gear S,. carrying resistanceconductor SF, is thrown into driving relation with the shaft L by theshift of the lever L and latter. This causes the disc S to be rotated inthe counter clockwise direction until the decrease in strength of theelectrical current flowing through the coils K and K of the balance KFpermits the frame K to return gear L carried by thev no i F, and p thedifference between the Pitot tube pressure transmitted through the tubeK and the static pressure. transmitted through the tube- K to thebalance KF, the relation between velocity, density and pressure may beexpressed by the following equation: p rio d where A is a constant. Theweight 'w of fluid flowing per unit of time is expressed by the equationqczBra where B is a constant. equations it follows that where C is aconstant equal to g, vThe relation between the balancing electricalcurrent, 2', flowing through the coils K and K and the pressure p, maybe expressed as follows:

where D is a constant. Hence a Ei /d where E is a constant equal toWhere the fluid flowing is a liquid at a constant temperature, v.or is apermanent gas at a constant temperature and pressure the density Z isconstant and the weight 'w, of fluid flowing is thenin constantproportion to the strength of the balancing electrical current 2'. Anammeter measuring the current flow through the dynamometer coils K and Kof the balance KF would, under the conditions just specified, furnish adirectmeasure of the weight of fluid flowing through the conduit F.W'here, however, the fluid is a liquid which varies in temperature, oris a permanentgas varying either in temperature or in pressure, suchvariations produce changes in density which alter the relation betweenthe weight 'w of fluid flowing per unit of time and the strength of thebalancing current i flowing through the dynamometer coils K and K. Ihave discovered, however, that the eflect of a change in gas or liquiddensity, due to a change in temperature, can be automaticallycompensated for by placing a suitable resistance, or net work ofresistances FR. in

the dynamometer circuit LF and locating.

this resistance FR in the conduit F, or otherwise subjecting it to thetemperature of the fluid flowing, and then instead of measuring thecurrent 2', measuring a potential drop due to the flow of the current 2through the resistance FR. The nature of the compensatingresistance andthe manner in which it elfects its desired result may be explained asfollows:

At ordinary temperatures and for a limited range between a lowertemperature t and a higher temperature t, the density variation of aliquid or of a permanent gas From these two' at a constant pressure,resulting from a change in temperature, can be expressed as follows:

l Vhere (i is the fluid density at the temperature t and a is a constantnegative coefli-- Cient, the value of a for air in the neighborhood of100 F., is about .OO2, and in the case of water at a temperature between100 F. and 200 F. is about -.0003. If 7* represents the resistance ofthe compensating resistance FR, and 6 represents the potential dropbetween the terminals of the resistance FR on the flow of the current 2'through the latter; then 6:67 The resistance r, for most resistancematerials out of which the resistance FR might be formed, will varv withthe temperature according to the following law:

e:ir [1+b(tt,)]. 7) being a constant coeflicient. From the precedingequations, we have is disregarded in the preceding equation). From thepreceding equations we have wherein F is a constant, equal to il. 7h

The value of the fraction a 1 i (t t, 1+b(tt,)

is constant if In other words, if the temperature coetficient ofresistance 7), of resistance conductor FR is equal to one-half of theair density coetficient a, the potential drop e across the resistance FRwill be proportional to the aaaeov 1 weight 'w of air flowing atconstant pressure per unit of time. "It is practically feasible to usein the resistance FR a material having a temperature coeficient ofresistance'b, equal to one-half the temperature density coeficient a, ofair or water as stated above. Carbon in one suitable form. may be usedfor air, and in another form may be used for water, since carbon in itsvarious forms has a negative thermal coeflicient of resist ance varyingfrom about .0003 to\.008. It will be apparent, of course, that if a bodyof carbon having a coefficient of .008 is connected in series with abody of some material such as manganin having a thermal coefficient ofzero or practically zero, the compound resistance thus formed may have athermal coefficient of resistance varying between .008 and-zero,'depending on the ratio,

of carbon to manganin in the compound resistance;

In the apparatus shown the air flowing through the conduit F is directlymeasured FR to a suitable ammeter indicated in Fig.1 at M, and in Fig. 6by m. The ammeter M, shown in Fig. 1, is intended for use in measuringthe balancing electrical currents passing through each of thevariousbalances KB, Ifll-KD, ICE and KG, as well as through the coils ofthe balance KF. For this purpose I associate with the meter M a timecontrolled switch mechanism forsuccessively connecting the meterto thedifferent balance circuits at regulan intervals. This switch mechanism,as diagrammatically shown in Fig. 1-, comprises a rotating switch arm Mconstantly rotated by a suitable clock mechanism M and connected by theconductor M to.one terminal of the meter M. The other terminal of themeter M is connected to a wiring system MM, which is connected in turnto one side of each of the compensating resistances-in circuit with thevarious balances. The switch arm M sweeps over and successively contactswith a circular seriesof stationary contacts M separately connected tothe different compensating resistances. Thus one of these contacts isconnected by the conductor ME to the opposite side of the resistance FRfromlthat to which'the conducting system MM is connected.

The compensating resistance -DR in the fluid fuel conduit D may beformed of carbon or carbon and inanganin. One terminal of theresistance'DR'is connected-to the common meter circuit MM, and the otherterminal is connected to the appropriate switch contact M by a conductorMD.

To measure'the quantity rate'of flowof.

the compressed air passing through the conduit E it is necessary to takeinto account variations in air density resulting from changes in thepressure of the air. This I meter 1L accordingly as the pressure in theconduit E, increases or diminishes. To thus vary the portion of theresistanceincluded in the meter circuit I provide a chamber E at theside of the conduit E' and open at itsinne-r end to that conduit,

and in this chamber I locate a piston E which tends to move outwardunder the action of the pressure in the conduit and to move inward underthe action of a spring E (see Fig. 10). I connect the piston E to aswitch arm E", which works along the resistance conductor EB. One sideof the meter is connected by the wiring MIW to the switch contact E andthe conductor ME. connects the appropriate terminal of the resistance ERto the corresponding stationary switch contact M With this arrangementthe portion of the resistance ER in circuit with the meter M will varydirectly with the pressure in the conduit 1*],- and hence will vary inproportion to the changes in density of the air flowthrough the conduitE resulting from pressure ch'anges' The variation inresistance of theportion of the. resistance ER in circuit' with the meter on changes intemperature will automatically correct, if the resistance ER is 1 madeof suitable material, for the changes in density resulting from changesin temperaturein the same'manner as compensa-' tion is obtained bymeansof the resistance FR,'3S above described. It will be apparent 106that with a constant pressure in the conduit E, the measuring apparatusassociated with it becomes; identical in principle and operation withthe measuring apparatus associated with the conduit F.. The dynamometercircuit LG of the balance FG, for measuring the flow of -satu-v ratedsteam through the conduit G, includes a compensating resistance GRlocated in the I conduit G. The'resistance GR can'notin 115 practice bea simpleresistance, but must be a compound or network resistance. Thenecessity for, and'nature of this compound resistance may beexplained asfollows:

The relation between density nd tem- 12 perature for saturated steam maybe repw sented for limited temperature ranges by large coeficient neededcan be obtained by making the resistance GR in the form of the networkshown in Fig. 7.

.As shown in Fig. 7 the resistance net work is composed of two parallelbranches,

each comprising two resistance conductors 1" and r in series with oneanother. The two conductors r are of the same material and of the sameresistance at the same tempera ture, and similarly the two resistanceconductors r" are identical with one another. Each resistance 1" may,and ordinarily will, differ from each resistance conductor 1* both inmagnitude and in the character of its temperature coefiicient ofresistance. The resistances 7" and 1" are connected in dif ferent orderin the two branches. @ne terminal of the meter M is connected by thecommon wiring MM to the junction point between the resistances r and rin one branch, and the junction of the resistances r" and 9" in theother branch is connected by the conductor MG to the appropriate contactM of the member M. The meter essee? thus measures a potential difierence6 which is equal to of the resistance conductors 1"- and r can beexpressed as follows:

1I/ ,nt1[ +f( v1] wherein a and f are constant positive coeflicients. Itfollows, therefore, that represents the current flowing through andthatchanges in steam density resulting from changes in steam temperature canbe compensated for by making the resistances 'r and 1'" out of suchmaterials and of such values that: g

r c-1'" ,f 1 1 By a suitable selection of ordinary resistance 'materialsout of which to make the resistance conductors r andr, and by a suitableproportioning of these two resistances, the value of the expressionlltlf Ta -"7 t1 can be widely varied and can be either positive ornegative though coefficients 0 and f be both positive. It is feasible,therefore, to

, employ a compound resistance such as is shown in Fig. 7 made out ofmaterials hav lng positive temperature coefficients of resistance, inlien, for example, of the simple resistance FR having a negativecoefficient of resistance, used in the conduit F.

The compensating resistance, see Fig. 8. included in the dynamometercircuit LC of the balance KC for measuring the flow of superheated steamthrough the conduit C comprlses a section r located in the conduit C,and hence'subjected to the actual temperature of the superheated steamand comprises other sections which are located in a receptacle Ccontaining water at the temperature of saturated steam at the samepressures as that ac tually existing in the conduit C. To keep thechamber C filled with water at the described temperature, the upper endof the chamber is connected at its upper end to the conduit C by a pipeC of suflicient length as to insure some condensation of steam therein.so that the chamber G which should beinsulated against excessive heatradiation. and is heated at the bottom by direct contact with theconduit C, will be filled with boiling water of condensation up to theoverflow limit provided for by the return passage C through which waterof condensation may flow back into the conduit C. With this arrangementthe water of condensation in the chamber C will always Y be at thetemperature of saturation of steam at the pressure actually maintainedin the conduit C. The resistances r and 7* form a networ: like thatshown in Fig. 7. and are,

similarly connected to the meter M. This network is in series with thereslstance 1'. and with the latter forms a shunt about the resistances1- and which are in series l r with one another. The resistances 5 and Edesired compensation may be explained as follows a temperaturecoeficient j;

.tion,

wa ed? The density a), of superheated steam, is

wherein (i is the steam density at saturafor the particular saturationtemperature t corresponding to the pressure of the superheated steam,and h is negative and has a value of approximately .OO135 for pressuresbetween 150 and 200 lbs. per sq. in.

In general it is necessary to compensate for pressure (saturationtemperature) and superheat simultaneously. by the arrangement shown inFig. 8, wherein 14 7' 1, r 5 and 5 designate and represent theresistance value temperature of the superheated steam. Assuming theresistance conductors r and r are both of the same resstance at the samethen if the dynamometer current for the balance KC is i, the currentthrough 7 will be This expression for any given saturation temperature ican be written temperature t the resistance values r r 7, g and;

are constant; and from the fact that the resistance value 1' at anytemperature 25 above vthe saturation temperature t may be expressed asfollows:

1' 7},[1 +L(t 15 wherein 1' is a constant equal to '1 when the latter isat the saturat on temperature t Since the potential diiference emeasured by meter M in Fig. 8 is proportional to the current z'a, wehave, expressing z'a terms of z, the equation:

6 i L+J(tt K being a constant. From this we derive:

This can be done and represents the resistance value of a resistancebody subjected to the 30 were straight lines,

But the weight rate of fluid flow may be expressed as we have seen interms of the balancing current 2' and fluid density as L we have Theproduct of the bracketed terms is approximately unity if since it is sosmall that the term 2 may be disregarded.

It follows, therefore, that for a flow of superheated steam through theconduit C at such a degree of superheat and pressure that the saturationtemperature of the steam is the assumed temperature t the weight ofsteamflowing will be approximately proportional to the potentialdilference measured by the instrument M, provided the resistances. areselected and proportioned in accordance with the foregoing principles.

Theoretically steam having a different saturation temperature wouldrequire adifferent arrangement of resistances, but in practice asatisfactory approximation to the weight of steam flowing may beobtained with apparatus calibrated for a single as.- sumed saturationtemperature notwithstanding substantial variations from the assumedtemperature of the actual saturation temperature.

The truth of this statement may be established by reference to a steamchart such as that shown in Fig. 11, wherein the abscissa: representsteam temperatures, and the ordinates represent steam densities in theunits expressed on the chart; and wherein 10 is the, steam saturationcurve and 20 and 30 represent constant pressure steam curves at and 200pounds per. square inch, respectively. If

and the lines 20 and 30 were parallel to one another, then anarrangement of the various resistance sections forming the compensatingresistance CR, which is approximately correct for one saturationtemperature would be equally correct for all saturation temperatures.While the lines 10, 20 and 30 are not straight lines the portions ofthem corresponding to considerable differences in steam pressure andsuperheat depart but slightly from tangents to the middle poznts of saidportions; and

the divergencebetween such tangents to portions of the l nes Q OVand 30is quite small. It will be understood, of course, that the departurefroni'parallelism between the lines 20 and 30 is greater than is thecorresponding departure between either of these lines and any constantpressure curve for a pressure intermediate those between lines 20 and30.

In the arrangements shown in Figs. 6, 7, 8 and 10, lobtain a measure ofthe quantity of fluid tlowing by creating an electrical currentproportional to the velocity head of the fluid flowing, and compensatefor the changes in density resulting from changes in the fluidtemperature by causing this electrical current to pass through a simpleor compound resistance maintained at such a temperature and having sucha thermal coetlicient of resistance that a potential dittterenceproportional to the weight of fluid flowing will be secured. Ameasurable electrical quantity proportional to the weight of the fluidflowing may be obtained in accord ance with the present invention by theconjointutilization of the pressure diiterential due to the fluid'fiowthrough the conduit. and the varying conductivity of a resistance bodysubjected to the temperat-ure of the fluid and varying in conductivitywith its temperature in other ways than that utilized in the arrangementshown in Figs. 6. '7, 8 and 10. For example. a device responsive to thevelocity head of the fluid flowing in the conduit. a current regulatorcontrolled thereby, and a resistance having a suitable thermalcoetli'eient of resistance may be utilized to create a balancingdynamo-meter current whichis itself proportional to the weight of fluidflowing, notwithstanding temperature created changes in the density ofthe fluid. and this method is employed in the B. T. U. meter illustratedin Fig. 9 for obtaining a measure of the amount of heat givento the'feedwater in passing through the feed water heater B. As shown, in Fig. 9.the B, T. U. meter comprises two resistance bodies It and two resistancebodies R. The resistance bodies R are similar to one another anddifferent from the resistance bodies R, which. however, are similar 'toone another. One resistance body 12 and one resistance body R *arelocated in the conduit B, and one resistance body R and one resistancebody R are located in'the conduit B With this arrangement when anelectrical current, proportional in strength to the quantity of fluidflowing, is passed through the circuit LB, comprising the two sectionsin multiple to each other. and each including in series a resistance Rin one, and a resistance R in the other of the two conduits B andneaaeor fully explained in my prior patent No.

1,267,757 granted on this type of a B. T. U. meter. The meterspecifically illustrated in my prior patent is open to the objection,however, that differences in the temperature of the fluid at the pointin the conduit at which the velocity head is measured will prevent thebalancing electrical current from being at all times truly proportionalto the weight of fluid flowing. v

With the improved apparatus shown in Fig. 9 the current flowing throughthe circuit LB is kept truly proportional to the quantity or weight rateof flow of the fluid through the conduit B; This ll accomplish byproviding a dynamorneter coil K for the flow balance KB, which issupplementary tothe balance coils K and K, employed with the other flowbalances illustrated. The supplementary coil K is connected in thecircuit'LB in shunt with a resistanee 7- having a suitable thermalooetlicient of resistance and located in the conduitB.

The manner in which compensation for density changes is made with thearrangement shown in Fig; 9 may be mathematically explained as follows:

w o 7 d a -wc-oi 0 being a constant. Then if 7 represents the resistancevalue of resistance body 7*, and r the resistance 1 5 value of winding Kthe pull of the solenoids:

' Pr 07/ W the term Pr W being the part due to the compensating coil,and O and P being constants. Then if r 11 is constant, and large inproportion to r,

is approximately equal to/Qi scribed the neaaeor Q and R beingconstants. 2' will, therefore, vary approximately as to when R7s:-a,remembering that a for water is negative.

in the apparatusshown in Figs. i and 5, T have illustrated amodification in which an electromagnetic counter balancing forcedirectly proportional to the strength of the current flowing through thedynamometer coils, in addition to a force proportional to the square ofthat current, is impressed upon the movable frames of the balance KK.This T accomplish by mounting an extra coil K on the frame KK with itsplane parallel to the plane of the oscillation of the frame and withinthe field of a stationary permanent magnet comprising opposedpermanently magnetized parts K and K With this form of flow balance itis possible to take accurate account of the fact that the head generatedby Venturi tubes, for example, is more accurately represented by thequantity And-BM, than by C0 v being the velocity of the fluid and A, Band C constants. in the apparatus shown in Figs. l and 5, theelectromagnetic counter balancing force may accurately be represented byEi-l-Fih By balancing this electromagnetic force in my apparatus againsta hydraulic force due to the head And-B12 it is thus possible byproperly choosing E and Rte cause i to be accurately proportional to '0.It will be apparent, of course, that where conditions require or make itdesirable an extra coil, as the coil K of Figs. 4 and 5, can be added tothe balances shown in Figs. 6, 7 8, 9 and 10, without in any waychanging the principles of compensatiouhereinbefore described as used inconjunction with those balances.

While in accordance with the provisions of the statutes 1 haveillustrated and debest modes of carrying out my invention now known tome, it Wlll be apparent to those skilled in the art that changes may bemade in the form of the apparatus disclosed and in the manner ofpracticing the methods described without departing from the spirit of myinvention, as set forth in the accompanying claims, and

those skilled in the art will understand also that certain features ofmy invention may sometimes be used with advantage without acorresponding use of other features.

Having now described my invention, What I claim as new and desire tosecure by Letters Patent, is:

1. In obtaining measurements involving the quantity rate of flow of afluid through a conduit, the method of compensating for changes in fluiddensity resulting from changes in the temperature of the fluid whichconsists in creating an electrical current whichis a function of thevelocity of flow, and passing it through a res1stance subjected to thetemperature of the fluid and having such a temperature coefflcient ofresistance that when said resistance is varied in temperature with thefluid, a potential diflerence is created by the flow of the currentthrough the resistance which is pro- .portional to the weight of fluidflowing.

2. The method of measuring the weight of a fluid flowing through aconduit which consists in maintaining an electric current proportionalin strength to the velocity of fluid flow and passing the currentthrough a resistance subjected to the temperature of the fluid andhaving a temperature coefficient of resistance so related to thetemperature density coeflicient of the fluid that a potentialdifl'erence will be created which is proportional to the weight of fluidflowing,.notwithstanding the changes in the fluid density temperature.

3. In obtaining measurements involving the quantity rate of flow of avapor through a conduit, the method of compensating for changes in fluiddensity resulting from changes in the temperature and pressure of thevapor which consists in conjointly utilizing the velocity head of thefluid and the variations in conductivity of a resistance varying inconductivity with its temperature, and subjected in part to the actualtemperature of the vapor in the conduit, and in part to the temperatureof saturation of the vapor when at the pressure actually prevailing inthe conduit.

4:. The method of obtaining an electric potential drop proportional tothe drop which would be obtained by passing an electric current througha resistance having one thermal coeficient of resistance and subjectedto a varying temperature by the use of two resistance materials havingthermal coeflicients of resistance diflering from each other and fromthe first mentioned coeflicient, which consists portions, eachconsisting of one section formed of one of said materials and a secondsection in series therewith formed of the other material, subjecting thetwo circuit portions to the same potential difference while subjectingthe end of one circuit at which a section of one material is used to thesame potential impressed on theend of the other circuit at which thesection of the other material is used, and while subjecting both circuitportions to said varyin temperature, measuring the potential di erencebetween the junctions of the two materials in one circuit and thesimilar junction in the other circuit.

5. The combination with a conduit, of means for maintaining an electricquantity approximately proportional to the weight rate of fluid flowthrough the conduit said means comprising a source of electric current,a resistance element varying in reresulting from changes in its informing two circuit.

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sistance with the temperature and subjected to the temperature of thefluid'flowing in the conduit, device responsive to variations in theproduct of the velocity head and density of the fluid flowingthroughsaid conduit, and an electric current regulator actuated by said deviceand connected in circuit with said source of current and saidresistance.

6. Apparatus for measuring the quantity rate of flow of a vapor througha conduit regardless of variations in its pressure or degree of superheat, comprising in combination a device responsive to the velocity headof the vapor in the conduit, an electrical current regulator, and acompound com pensatingresistance comprising a section and means forsubjecting said section to the actual temperature of the vapor and asecond section and means for subjecting said second section to thesaturation ten'iperature of the vapor corresponding to the actualpressure in the conduit.

7. Means for measuring the weight rate of flow through a conduit of avapor of varying pressure and superheat comprising an electric circuithaving two branches in shunt to one another and formed of materialvarying in conductivity with its temperature, means for subjecting oneof said branches, and a portion of the other branch, to the saturationtemperature of the vapor at the pressure in said conduit, and t'orsubjecting another portion of said other branch to the temperatureactually prevailing in said conduit, means for passing an electriccurrent, proportional to the velocity of flow in said conduit, throughsaid circuit, and means for measuring a potential difference createdthereby in said first mentioned portion of said other branch.

8. In combination a conduit and means for measuring the flow of asuperheated vapor through said conduit comprising a vessel in heatconducting relation with said conduit connected above its lower end tosaid conduit by a passage adapted to condense vapor flowing through itinto the vessel from the conduit and by an overflow passage adapted toreturn liquid of condensation to said; conduit and means for maintainingan electrical quantity proportional to the weight rate of flow throughthe conduit comprising a current regulator responsive to the velocityhead in said. conduit and an electric circuit on which said current reulator acts and which circuit comprises an electrical resistance elementlocated in said vessel and thereby subjected to the temperature of saidvapor when saturated at the pressure actually prevailing in saidconduit.

9. In combination a conduit and means for measuring the flow of asuperheated vapor through said conduit comprising a vessel in heatconducting relation with said conduit and means for equalizing the vapori pressures in said vessel and conduit, and for permitting liquidaccumulating in said vessel to overflow intosaid conduit, and forsupplying liquid of condensation of said vapor to said vessel and meansfor maintaining an electrical quantity proportional to the weight rateof flow through the conduit comprising a current regulator responsive tothe velocity head in said conduit and an electric circuit on which saidcurrent regulator acts and which circuit comprises an electricalresistance element located in said vessel and thereby subjected to thetemperature of said vapor when saturated at the pressure actuallyprevailing in said conduit.

10. In a flow balance the combination of a differential pressure gaugecomprising a movable part subjected to a force proportional tothepressure'diiferential to which said gauge is subjected, and balancingmeans comprising a cooperating pair of dynamometer current carryingwindings, one sta tionary, and the other mechanicallyconnected to saidmovable part, and a second electromagnetic device comprising a currentcarrying winding portion and a cooperating permanent magnet portion, oneof said portions being stationary and the other being mechanicallyconnected to said movable gauge part.

11. The combination with a conduit, of a resistance element varying inresistance with its temperature and subjected to the temperature ofthe'fluid flowing through the conduit, means responsive to the fluidvelocity head and density of the fluid flowing through said conduit forpassing through said resistance an electric current which is a functionof the product of the velocity head and density of the fluid flowingthroughsaid conduit, and means for measuring the potential drop in saidresistance.

GEQRGE H. GIBSON.

